WASHINGTON — Refusing to rule on the merits of the case, a federal judge Tuesday night rejected an Arizona sheriff’s lawsuit seeking to halt President Barack Obama’s plan to spare nearly 5 million people from deportation. U.S. District Judge Beryl Howell said the role of courts is not to engage in policymaking that is better left to the political branches of government. The case brought by Maricopa County Sheriff Joe Arpaio “raises important questions regarding the impact of illegal …